Decreasing device size and increasing device density has traditionally been a high priority for the manufacturing of the integrated circuits. Optical lithography has been the driving force for device scaling. Conventional optical lithography is limited to about 80 nm pitch for single exposure patterning whilst double and other multi-patterning processes can realize smaller pitch, these approaches are expensive and more complex.
Directed self-assembly (DSA), a technique which aligns self-assembling polymeric materials on a lithographically defined guide pattern, is a potential option for extending current optical lithography beyond its pitch and resolution limits. The self-assembling materials, for example, are block copolymers (BCPs) which consist of “A” homopolymer covalently attached to “B” homopolymer, which are coated over a lithographically defined guide pattern on a semiconductor substrate. The lithographically defined guide pattern is a pre-pattern that is encoded with spatial chemical and/or topographical information and serves to direct the self-assembly process and the pattern formed by the self-assembling materials. Subsequently, by annealing the DSA polymers, the A polymer chains and the B polymer chains undergo phase separation to form an A polymer region and a B polymer region that are registered to the underlying guide pattern. Then, by removing either the A polymer block or the B polymer block by wet chemical or plasma-etch techniques, a mask is formed for transferring the nanopattern to the underlying substrate. Unfortunately, current processes for forming chemical guide patterns for DSA are complicated, costly, and/or not practical for large scale manufacturing.
Accordingly, it is desirable to provide methods for fabricating integrated circuits including formation of chemical guide patterns for directed self-assembly lithography with reduced complexity and cost and that are practical for large scale manufacturing. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.